Computing gun sight



Dec. 1, 1953 c. GOERTZ HAL 2,660,794

COMPUTING GUN SIGHT Filed Sept. 12, 1942 3 ShGGt-She6t l Fl G. 2 I4 24GUN CONTROL SERVO MPLIFIER CONTROL AMI? 16 7 FIGS J I41 I24 222 H 4.}l

All A fllll A s'Qio 3J5 44 SIGHT CONTROL g SERVO AME INVENTORs RQGCERTZH.L.HULL

yZV/Z ATTO R N EY R- C. GOERTZ ETAL Dec. 1, was

COMPUTING GUN SIGHT Filed Sept. 12, 1942 3 Sheets-Sheet 2 MOTION orTAJGET TIME 0F Fl/Gl/i' 04M 7 mil:

TORQUE AMPLIFIER Patented Dec. 1, 1953 UNITED r STTETS '3 Claims. 3

Th present irrvention'is related to the art including computinggun'sights and gun turrets.

The present invent-ion is especially concerned =wi'thc'omputing g-unsights of the type in which 't-he' 'si'ght is carried by or moved insynchronism with" the gun or turret and is onset or disturbedwith'respect to the gun by the amount necessary to give the proper leadangle of the gun with respect to the present orientation of the targetdefined by the line of sight of the sighting mechanism; to properlydirecta projectile to the target. Such a sighting-device is shown incopending application Serial No. 353,382, forComputing Aircraft GunSight, filed September 26, 1946, in the names-' ofC. Gofiolschuh and O.Vielehr, now Patent 2,396,701, g'ranted March 19, 19%. oomputing'gunsight'of' this prior application is The intended fordirectmanualoperation in an aircraft. "The present invention constitutesan improvement of-and a simplification of the gun sightof the priorapplication, including a manually controlled power means for rotatingtheguns and a simplifiedlead computing mechanism suit able for useeithe-r'on aircraft or on the ground,

against any moving targets.

Disturbedgun sights of the present type are subject to a type ofinstability which renders their efficient operation "very 'difiicult.This instability may be seen from the consideration that,

if the line of sight should be lagging behind the target, and the gunnerdesires to move the line'of sightup onto'the target, hisnaturalactionis' to increase the'velocity of tracking of the gun andsight. In so'doing, thelead angle also increases,

since it has one component (predictiom proportionahto the angularvelo'city'of the guns, and ther etor tends-to driv'e -the sightbaclvwith 5 respectto. the gun and away'from the target. Thisconstitutes an unnatural response-to the" natural tendency of theoperator, and results in confusion and difliculty in a'curately''maintaining t'he line of-sightintrackwith the target.

"This objection" to the disturbed sight is-;overcome by the presentinvention,- and-a further advantage in-simplified tracking is obtainedby pro 'vidi-ng a- 'contr'ol-of the sight-which at the-first instant inresponse to a change in velocity, moves the sightiorwarch namely; in thedirection of the target; rather than reversely; as has formerly been thecase. This temporaryforward motion is then-wiped-out and reversed toprovide therequire'd lead'angie aftera time delay sufiicient to preventthe unstable operation'referredto above. In this manner-an aidedtracking typeof control of thesight'is obtained; whi'chhasbeen'iound tobe advantageous in facilitating accuratetracking with a moving target.

In addition,- the present invention provides the furthenfeature thattheorientation of the sight is rendered independent-of'the computingapparatus-and is controlled solely-hy the manual control-cf theoperator,"whereby" the effectof change in the lead an'gle does*not'impai'r the ease-and effectiveness'oi control of the'track'ing.

Accordingly; it is an object of the -present' 'invent-ion to provideimproved computing -gun sights'of the fdisturbednighfi type, eliminatingthe" unstable operation of prior art systems;

It is a further object of the presentinvention to provideimproveddisturbedgurr'sights in'v'vhich the sight isinsta-ntaneouslyactuated in a-"direction to follow the target upon a change of theposition'of a manual control, and is thereafter delaya-bly mov'ed intheopposite "direction to introdnce the reqrrired lead" angle betweemthesight and the gun.

It isa still'fur'ther objector the present invention-to'provide improveddisturbed gun sights incorporating'anaided'tracking type of control of'the sight.

It is-another object of the present invention to "provi'deimproved"disturbewgun -sights in which -the"-"eoi'itrot of 't-l'ie-oi'iefltation' o'fthe-line of sight is made independentof the leadangle, *whereby ease oftracking is greatly improved:

Itis= still another object "of thepresent' inventionto provideimproveddisturbed-gun sights including means for delayably offsettingthe sight by the required lead angle to prevent unstable operationytheamount-of delaybeing adjusted in accordance with the projectile time offlight" to provide improved *operation'both' with dist'a'ntand withclose-in targets.

It 'is'a' further object of the' present invention to "provide "anelectrically operated disturbed gun sight incorporating at least some""of the advantages' described above.

It is still another object "of the present invention toprovideasimplifiedmec'hanical construction for a disturbed gun'sight alsoincluding these advantages."

Other objects and: advantages will become apparent-from thespecification, taken in connection with' "the accompanyingi'drawingswherein the'inventionis embodied in concrete form.

'In the'drawings;

"Fig. 1' shows a schematic. perspective view of arepresentative'gun'turret, such as maybe used with'the'presentinvention.

*Figi? showsa schematic circuit diagram of an electrical embodiment ofthe control for a disturbed gun sight according to the present invention, showing the control along one coordinate.

Fig. 3 shows a diagrammatic view of a mechanical embodiment of thepresent invention for controlling the device of Fig. 1.

Fig. 4 shows a schematic diagram of a complete mechanical embodiment ofthe present invention, including the features and advantages describedabove, and V Fig. 5 shows an improved form of the circuit of Fig, 2.

Fig. 1 shows a schematic perspective representation of one form of guncontrol and sight. In this case, the guns I I are mounted on a platformI2 for rotation about a suitable axis, in this case illustrated as beinga vertical axis, whereby the guns I I may be rotated in azimuth. Alsocarried by platform I2 is the sighting device, illustrated schematicallyas being a telescope I3, which may be any type of device adapted todefine a line of sight to a distant target. I

By a sighting device in the present case is meant any device defining anaxis and capable of indicating or determining when this axis is orientedtoward a target, and may include radio, infra-red, photoelectric orother devices as well as the usual optical telescope or sight.

Platform I2 is adapted to be rotated in azimuth by means of a suitableservo device I I which drives a inion I6 engaging an internal fixed ringgear I'I, whereby the platform 32 is caused to rotate by the interactionof pinion I 6 and fixed internal gear I'!. Servo I 4 is controlled froma manual control member I8 by means of suitable control mechanism,indicated by the control box I9.

Manual control member I3 and its associated circuit are preferablyof thetype disclosed in Figs. 12A and 12B of copending application Serial No.428,036 for Positional Control System, filed January 24, 1942, in thenames of H. L. Hull, R. C. Goertz and W. C. Hartman, now Patent No.2,526,665, or in Figs. 2-4 of copending application Serial No. 403,618for Handle Control Systern, filed July 23, 1941, in the names of H. L.Hull, W. C. Hartman and R. C. Goertz, now Patent 2,414,102, grantedJanuary 14, 1947, and are adapted to produce an electrical voltagecorresponding in sense and magnitude to the sense and magnitude ofdisplacement of control member I8. As shown in copending applicationSerial No. 428,030 in its simplest form, the means employed forconverting the displacement of control handle I8 into a correspondingelectrical voltage signal may comprise merely a resistive potentiometerwinding having its opposite terminals connected to a constant source ofalternating or direct potential, and having a movable contact armactuated by control handle la. The voltage between the contact arm andthe midpoint of the resistive winding then provides the requiredelectrical control signal.

Fig. 2 shows one form of control circuit which may, for example, beincluded in control box I9 in Fig. 1, operative in response to thecontrol signal produced by the control member I 8 to orient the guns II. Thus, the control signal derived from the manipulation of controlhandle I8 is connected to input terminals 2I, and is thereby impressedacross resistor 22; Resistor 22 is connected in series with a resistor23, whose function will be described below, and the resultant seriesvoltage across these two resistors is impressed upon the input of anysuitable conventional type of amplifier 24. Amplifier 24 is preferablychosen to have a large amplification, whereby it may produce full outputvoltage for a very small input voltage. The output of amplifier 24 thenactuates a suitable servo device It. Servo I4 may be of the well-knownVickers variable-speed hydraulic transmission type, in which apredetermined input control signal voltage produces a corresponding andpreferably proportional rate of turn of its output member 28 connectedto pinion l6, shown in Fig. 1. If desired, any of the servo devicesshown in Figs. IDA-10D of application Serial No. 428,030 may be usedhere.

Connected to be rotated simultaneously with platform I2 is a generatoras, shown for example as driven from a pinion 3I journaled in platformI2 and connected to generator 29 by any suitable mechanical means,indicated at 32. Generator 29 is preferably of the type which producesan output voltage directly proportional to the speed at which it isdriven, and this voltage is impressed upon resistor 23 in series withcondenser 33 This voltage is of the same type (alternating orunidirectional) as the signal voltage impressed across terminals 2i.Preferably, generator 29 is of the permanent magnet direct current type,and the control signal is unidirectional or is converted suitably into aunidirectional voltage across resistor 23.

Neglecting for the moment the effect of condenser 33, it will be seenthat the control signal voltage impressed on resistor 22 will serve toactuate servo I i, and thereby sets up a rate of turn of platform I 2.This rotation of platform I2 produces a voltage by means of generator29, which is impressed upon resistor 23 to oppose the voltage acrossresistor 22. By making amplifier 24 sensitive and responsive to smallvalues of in put voltage, an equilibrium condition will be reached inwhich the voltage input to amplifier 24 is just that necessary toproduce a rotation of platform I2 and generator 29 such as to produce avoltage across resistor 23 diifering from that across resistor 22 onlyby the small amount necessary to actuate amplifier 24 to maintainoperation of the rest of the system. Since the voltage output ofgenerator 29 is proportional to its speed and that of platform I2 andguns II, it will be seen that in this way the control signal voltageimpressed on terminals 2I, and therefore, with condenser 33 omitted, thedeflection of control member is, will be substantially proportional tothe angular velocity of the guns I I and that, in effect, a rate type ofcontrol is provided, as described more in detail in application SerialNo. 403,618, in which a predetermined deflection of manual controlmember It produces a corresponding angular velocity of guns II andplatform I2.

Condenser 33 serves to provide a type of integrating or smoothingcontrol. Thus, if the guns II and platform I2 are being rotated at aconstant angular velocity, a constant voltage will be generated bygenerator 29 and will charge condenser 33 substantially up to thisvoltage. During the time condenser 33 is charging to full voltage, theVoltage across resistor 23 will correspondingly decrease since the sumof the condenser voltage and the resistor voltage must continuously beequal to the voltage produced by generator 29, which generated voltageis constant if the platform has a constant angular velocity of rotation.The deflection of the control handle I8 necessary to maintain thisconstant angular velocityzof platformzelfl will continuouslyidecrcase.sincerin nrderg-tormaintain -;aa:constantaangidarvelocityiof'zplatiormrfi: the displacement.:nf:;-controhrhandie -:Rl '81:inust be .alwaysrjnsmsufficientito :produceiacontrolsignahzoltage=a-crossrresistorz22 w hichzcdifiers *f romzthe.iyoltageraorosscresistor r23 oy the smalhcionstant'amount necessarytozmain- .tainathis uangular :velo'city. i'Ihe-areqnired Edis-;placement; will theneforeradecrease asoondenser 33 vchargesstand the:yoltageraacross resistors-r23 decreases. =.a'Ihus,"-aftertabringingthe;pl-atiormaand guns up :to' the desired angularl'veloeityiitheicontrol {member .18 zmay :be agraduai ly returned: to: its neutrahposition VZith0llb'-.rchangingljhe angular velocitynf thetp-latform.this way, vcondenser 33 operates i110 .cause' the platform :l2 and gunsI i-tohcontinuerto rotateat the same velocity: even aftertamanua'l.controiler 18 is 1 returned ato its neutral position-.r 2

: Sighting idevice I 3 is; a'lsoaoarried' by platform '12,ibutadiustablewith:respect thereto by means ,of servo 412, so-that iftheimanual controller 1 8 is adjustedfso that-:theJimeof sightdefinedeby sighting device I3 is tracking with :a tar'getyit Will the.clear that the guns. I l are movingat the same angular velocity as thatof the target rela ztiveito theigun position. 1;

If aij-projectile isifire'drsby the-"gun, itwill take -a predetermined:time interval, known itime ot'fii'ghtfibefore reaching the-bargeingzizthis time of: fiight the: target will have advanced' it'sposition-:by an amount-roughly equal to: the angularrveloeity of theitarget relati-ve 'to the gun positionltimes :the timezofflight-which istermedl the predictioni lead' angled Accordingly iin order to permit"the gun to effectively direct the proj ectile; the orientation of 1thelgun must be advanced with 'respect to the' orientation Lof.th'eitarget by :anamount corresponding' -to this leada angle; In -"thepresent:systempthis is don'e by retarding theisig-htingdevice "13*relative to --platfiorm' F2 on which itai'scarried and -to the guns 1-!thus producin c "disturbed gun sights "For 'thiscpurpose; it'willebenotedthafi' the' v'olt age' produced by igenerator" 29 is proportionalto the angular velocity of the platform- 1laifid gdns 'I-l andhence;when. the 'sighting"device 113 is tracking with the 1 target, willalso be sabstam tially -proportionalr to the angu lar =veloeity of= thetarget:

' To' multiplythis voltage by the time assigns, I

a potentiometer-35 is connected-across the teriminals of generator It--\vill --be=-c1ea-r=tnat the vo1tage der-i'ved between" the variablearm Sfi of potentiometer- 34' and one ofits fixed terminals will beproportional to the""defl'eetiori- =of-a1m-36 from its "end position'and will also be propors tionalto the voltage-impressed across theentire potentiometer "-34, that-is, will" be proportional to thevoltage-of generator 29, which hasalready been shown to be 'proportional totheflg-un or target angular --ve1oc-ity 1 during proper trackingconditioxis- Thereioregby suitably 'ad'justing arm '36, as by means ofa-knobfl, proportionally to time of flight, the 'outp u-t voltage iromrmtenti ometer- 3 1 may be taken -as proportional-tothe product oftarget angularvelocity and-*the 'time of flight;- sinoe time 'of flightis'approximately a function only ojtarget range;knob fil-inayheprovided' with a suitable-scalecalibrated di'rectly :magnitndes,qthezsight :13 :may be angular-1y displaced from thezorienta-tion :ofthe gunsrljlaby exactly theproperlead angle iowprovidezso-oakled fnediction-ecorrection: or prediction leadeangleiorrthegunsgtoxallowdor'the motionzobthe target;relatlye;tothe;gnns.ii-" r alt will-c bB'J'SEEIl-thtt if gunsl lvaremovingfifor exaample, :clockwiseginrFigml; sight at3-';mustf'bedisplacedjnzacounterclockwise sensexvithmespeet r110 platform [2. a Ifthesight '13 is-tracki-ng behind thentarget; and thel'gunner; attemptsto accelerate theasight' to "-iget "on :the. target; "it will .;be; seenthat: any: .increa'sez'in gun and :platform :izelocifiy Will produce adisplacement?ofxsight :13 itending to increase the :lagbetvzeenvsightsand"targetpand the-more the gunvelocity:is:increased;theigreater lag :isproduced, although. the gunner:is'attemptingto decrease theilag; Thisaction islcharacter istic et all:disturbedl'sig-hts, and renders tracinihg with the target yeryszunnatural tand'xiiffioult, thus preventing-optimum:utility:.ofa thedevicem To overcomethis defectgacondenser s46 arid'sa resistor 41 areconnected across-'thehinputiters minals 121 supplied a with: thecontrolz signalx.and the voltage across resistor fl 'l isfinsertedin'sseries :across s the voltage :output: .of the: rtime of-flightpotentiometer-M and-is therefore addedithereto. The values .ofcondensersllfiaand resistorztlsa-re chosen: such :that' sthese elementsform "ca differentiating :circuit i-n a: manner :well s-known Ii-nthexart, whereby thesnvoltage derived across =resistoriAflcorresponds-"to the rate of change of the control signal impressed onterminals 21. 7

:By. adding: this voltage to the lead 'angle. :volt- -34; the sightalz-ais initially actuated'in .suchiaa mannernasto follow theztarget, ratherthan in the; :opposite zsenseiuas would otherwise' be ime ease-e c Y LThis:actionservesto ovencomethetracking 'lag andthe sightcatchesiupirto'theLtarget. ;At this instantg-iiof courseuthefoorrect1ead:.ang1e isrnot present, :hutthis is immaterial :since firingktzis'done only while accurately "tracking the targets: In this way',:thetsight:respondsads the o zzeratorwould "intuitively expect, "and: notoppositelm and thong-aerator is enabledito getiorr the ta'rget-muchmorequickly to 'placeathe sight theiproper tracking condition.

: .711; will be seen: that the rate voltage derived from resistor 4 1'wfill die out as the control-signal persistspand-that after a short timethe-actual lead angle between sight 13 and-guns II will again becbme---proportional to the lead angle voltage,- a s is: required, whereuponaccurate-fire can be obtained once more.-' In thisava-yastable and easilyoperated disturbed gunsight system is provided; eliminating theinstability charactcri-stic-of'prior'art devices.

x Tli-diffrntiatingcircuit 46, 47- alsoproduces 7 a type of aidedtracking control for the sight. As is known, in an aided trackingcontrol, the controlled device is actuated so that its displacement froma predetermined neutral position is related to a constant displacementof the controlling member by a relation of the form 0: knp +k2q2'b wherek1 and R2 are proportionality constants and t is the time the controldisplacement persists.

In the present case, the motion of the guns and platform carrying thesight produces the second term of the right member of the abov equation,while the differentiating circuit 4%, 4? produces the first term, atleast in transient fashion, during getting on the target, when aidedtracking control is most useful and desirable.

It is to be noted that the device thus far described serves to supplyonly the prediction lead angle. Other lead angle components may also beprovided by inserting voltages proportional thereto in series with theinput to amplifier 4!.

The system of Figs. 1 and 2 has been described with respect to motionabout one axis only, illustrated as being the azimuth axis. It is to beunderstood that preferably the guns 1 l and sight 13 are made rotatablealso about a second axis, such as an elevation axis perpendicular to theazimuth axis, under the control of a suitable manual control member,which may be member 18, displaced about a second independent axis, as isshown below in Fig. 4. A similar control between the elevational motionsof the sighting device 13 and guns ll may be provided for motion aboutthe elevation axis, as shown in Fig. 4, whereby the gun sight of thinvention may be utilized with targets moving in three dimensions, suchas aircraft.

The system of Fig. 2 still suffers the disadvantage that the gunner, inorder to maintain the sight in track with the target, must actuate thesight (by means of his control of the guns and platform l2) tocompensate for changes in lead angle. It is preferable, from thstandpoint of simple and effective tracking, that the operator be ableto manipulate the sight without adjusting for changes in lead angle.This is done in Fig. 3, which shows a modified type of control systemsimilar in principle to that of Figs. 1 and 2, but entirely mechanicalin operation. Here control handle I8 is coupled to arm 50 and displacesthe ball carriage 5| of a variable speed drive 52, whose drive disc 53is rotated at constant speed from a constant speed motor 54. In'thisway, the output cylinder 56 of variable speed drive 52 is rotated at anangular velocity proportional to the displacement of control l8. Thisrotation of cylinder 56 is led through suitable gearing 5'! and adifferential 58 to rotate an output shaft 59 which is connected by wayof gearing 6!, shaft 62, gearing 63, and shaft 64 to a torque amplifier66 whose output 6'! drives pinion IS with respect to fixed rin gear I Tin the same manner as in Fig. 1. Torque amplifier 58 may be of anysuitable type adapted to provide a high torque output from a relativelysmall torquev in put derived from shaft 64. Such amplifiers are wellknown in the art and are believed to require no further descriptionhere. One form of such torque amplifier is the well known Vickershydraulic variable speed drive.

In this manner, displacement of manual con trol l8 sets up acorresponding angular velocity of platform [2 which carries all of theelements shown in Fig. 3, except the fixed ring gear IT,

in a manner similar to that shown in Fig. l,

and hence provides a rate control of sight l3.

At the sametime, the displacement of manual control I8 rotates a lever68 about a pivot 69. Lever 68 is connected through a further linkage H,12 to the sight I3 and thereby displaces the line of sight M,corresponding to the optical axis of telescope 13 in Fig. 1, by aproportional amount and in' the same sense as the desired rotation ofplatform I2, as to a position 14 relative to the gun orientation whichis along 14. This action therefore corresponds to the effect ofcondenser 46 and resistor 41 described in Fig. 2, since the sight I3 isthus initially displaced proportionally to the angular velocity ofplatform l2, and provides a resultant aided tracking control of sight13, which has been recognized as a desirable type of control forefficient tracking.

At the same time, displacement of control member l8 moves another lever16 about a pivot 11, which motion is transferred proportionately througha link 78, link 19 pivoted at 8i, link 82, and lever 83 pivoted aboutpivot 84, to proportionately displace ball carriage 86 of a secondvariable speed drive 81 also actuated from motor 54.

The rotation of output cylinder 88 of variable speed drive 91 rotates ashaft 91 carrying oppositely threaded screws 92 and 93 cooperating withrespective traveling nuts 94 and 95, upon which are mounted the pivots8| and 69 described above. Thus, the rotation of shaft 91 serves todisplace pivot 8|, whereby lever I9- pivots about the new position ofits pivot and returns the ball carriage 86 to its neutral or centralizedposition to stop the. rotation of shaft 9|, which will then have rotatedthrough an angle proportional to the deflection of member l8.

At the same time, rotation of shaft 9| operates to move the travelingnut 95 carrying pivot 69, whereby lever 68 pivots about its pivot 10 andturns the sight I3 oppositely to its original motion. The angulardisplacement of shaft 9|, and hence the angular displacement of sight l3thus produced, will be proportional to the displacement of manualcontrol l8 and accordingly will be proportional to the angular velocityof platform I2, which will be equal to the angular velocity of thetarget during proper tracking.

It will be seen that this angular displacement of sight l3 and shaft 9|will depend upon the position of the pivot 11 about which lever 16rotates. This pivot is made adjustable, as by means of a time-of-fiightcam 96 and a slide 91 actuated by a range knob 98, and is set inaccordance with the time of flight of the projectile, determined in thesame manner as with respect to Figs. 1 and 2, from a suitable rangefinder. By adjusting pivot 11 in accordance with the time of flight, theangle through which sight I3 is turned by shaft 9| is made proportionalto the time of-flight plus a constant. Since the original deflection ofsight ii! in the direction of motion of the guns was proportional to theangular velocity of the guns as determined by the angular displacementof control r8, this constant is chosen to be of such value that theresultant position of sight l3 will be displaced from the orientation ofthe guns by an amount equal to the desired prediction lead angle, or tothe angular velocity of the guns times the time of flight, producing thesame type of operation as in Figs. i and 2.

The motion of output cylinder 88 of variable speed drive 81 is alsoadditively coupled to that asses-94 of; cylinder 5.8? by -way:ofigearingfiil and; difierem tia1158z Irrthis wa'y the-input to: torqueamplifier: fifiijandthe platform ,IZ'i are add-itionally displacedi byaJ-com-pon'ent corresponding tothe Epredictionr Iead'angIe; 5

- -Since;the sight; I-3 is displaced relative-rte. platform. I 2andguns- I I bywthe same amount.- as: their "guns and: platform f are Ioppositely dislplacedz with-respect to: theita-rget; it: wiliihe-seenthat sight. It has no;- motionzrelatiice-toethe target: dueieto the:3617101121 of Wariabl'ev speed? rdrilver- 8-1;; whichitherefore setsinthe proper'lead anglezwiths-x out; infamyway"v impairingzthe'i ease: of:tracking..- Imothen words, thea'gunner needznot compensate for.theisleadzangle; as, he must-din Fig. 2;.

- It. will bexseen thairvariable speedrlrive Bifacts. to initially delaythe control; ofnsight I-3=1byather prnperfleadjangle, rsotithateasieriandis-tablatracking:;is possihle; This; delayis"controlledtby'sthe settling time? of: drive 81;? which is 'itheirtim'eiitgztakesi. to resume ar'stable posit-ion: after being displaced, and.depend-s on: the. speed; off motor" Etemd :the';amount;thevballtcarriage lfifiiiscinitially displaced, which; latter.in.- turn'z 'depends= onus the; distance [advantage .ofzthe lever system83 ;'18'2;;etcir 'I-his;;:set.tling time, inrth'eidevice: dffFigi: 3;:-is; selected-s to; have a; value: large enoughi toi uprovide stabletraokingbyzsight -I:3;"andfshort=enough' to: obtainquick settings OffthEsight and guns to the'properrfiringpositions; I 1

It: williberclearkliere ialso'sthatz arsimilarrc'ontrol:maybeg-providediformotion abouta second axis" perpendicular. tothe-axis-of rotation of-ssight; I3 and the guns; to' provide.three-dimensional con trol. I

-To yide control-icompensaitioni forthe'lead' angle niFig; 2;this:cir?cuitzrnaybe modified in: the-:manner: showrrin 5; by the-additiomof: agenerator-"45 driven fromithe'fis'ight servo 4 25syn:--chrbnouslyz withe-sighti I 32- Generaton 45 ='ispref erabl-y of: thesameitype' asiigeneraftor 2'9',iand:prot-- dizcesaa voltage output=prop'ortiona1 to: the speed atawhichzitsiszdriven; whichwill thereforebe proportional'a to the ratelofi change of'ithe prediction:

lead angle. 1 Thisipredictionirate voltage is' in' 5 sertedz in series:with; the :otheflvoltag input" tocontrol amplifier 241 As wa's seenzz-ithe speed 50f i-th'e 5 guns obtainedfifromr g'urrservo I isproportional'totm input yol-tageeiierivds'across resistor. '2 21In1Fi'g. 5,:however, the: 'gun rate willa beinroportional" to the sum;of i the ivoltagei across resistor 2-2; and theivoltage derive'cl' fromsgenergator}; 45: Aceordin'glm the: gun -torientation:-de-'- rived-byithetdeviceuof Rig; 5.-in respons'e."150:3;v change in displacementof't'controli I8; willibe-ad' vaneed'i from? the;corresponding"orientationofi' th8.'l1lfllifli Fig.-. 2-: by "an? amount;equal-"to; thee 'change-ain the dead tang-1e; so;thatwthefisightt and;

from potentiometer S it-resistor and'potentiomiffio"etertfi-gdescribed"inFig:2.1

I Figs; 4 shows L a :modificatiori: Of! the =-device:;of: i:3';inchrding:lcontrohalonggbotlr eleyationgandj azimuth coordinatesand; incorporating i seyeraL improvements.{ Itrv will ?be; noted that.thei'devioefla;

1 i bfli-tyfofz'operation wand easeof. tracking. s:-

dependenti faxes; i corresponding-to L axis'varrd'ithaazimuth iaxis 'ofrotatioli ofwtlf g'un I isr-desiraiblethataishort'rsettling'tinre bepr'vided in: orderrto? enable lithe gunner tc' quickly get 'into theaccurate firing-.1" conditions E01 longerranges.andelongen times oftflightpailonger set tling tiInedsi desirable to pro'vide improVeds'tafeature is alsb'iiicorpbrate'ddn the device of FigReferringitosthisi figure, the sight I3 is shown: as -'constituting'xamirror "I (H I pivoted-1 about an: axis 5 I 02. preferably horizontally*di's'posedi and parallelitb theselevation trunnions of the gun:ands-eo'operating 'withra secon'dmirror I 03 1'aifioted about. an:axis": "I or: disposed along the axis or the gun. A; suitable: sourceaof light; indicated "sche-' matically" asa a :lamp bulle I06;p'ro'j'cts us -1am: rays-1through-:ascreeni or:' n1asking merxfber: I 81havingsa; suitable-I'reticl'e 'l I18? fofmed 'thereofi; so thattherimage ll-II ofr t'his: reticl' is -refleeted from; mirror I03nth-mirror 'I 0 I, and-- tliereby intb the"'eye' 'I09;-tof1=the gunner;=Mirror-'- BI thiS DIane. Thisum'a'it be? termed? motion in: gun

slant gplanei azimuth; Rotation of: mirror "I III will cause-5thisireticletimag I Fl 0 to :aph'ean tonrove perpendicular: tor-axis: I-02;:producing IIIUl'ii'Oh'E'Df? xelevation; 'As will b 'seerii.

the diner of sig mirrorsrrl III antf -I 03*Ear angularly 'displaoed inaccordaince' rwith the? elevation and +s1an'tiplaneazinruthiicomponentsiof 'i'thz -le'adi angleerequired c for properoperation, and therefore 'thei op'ticali system; I 3-;is'1 operatedii'nazsiriiilar' fashionwt'o' that of zEigsizian'd' 3, :hav ing itsi-ilinei-ofisight offstor: di'sturbed'irom the gun orientation by theamount and-Lim the direction ofzrthe rres'ultant" lead "angleIrrzoperation; the? gunnermrill actuate theman ual controller-E I8%toimaintain 'the target central 1,;ized'rzwith'z'respeet: to th'? 'reticleimage H0} at which; ztiin'enp-the proper tracking condition forefiectivefirez' haying-independentdisplacement about two in"a-.=member:-1I lzh formed a's: ar sectori of a r-cireleiFhavingi-itscenteralongatherpivotfiaxis:I I 2 of' tlre m2111- obtained;"htanualicontr'ol z'mem benc'l 8-- im-Figz; 4'; isishowni as being'l ofthe? type e elevation;

ence of this circular member I I I is a cable II 3 which is maintainedin close contact with this circumference by means of an idler pulley H4.Upon motion of manual control I8 about axis I I2, cable I I3, operatingagainst the pull of a spring I I6, whose remote end is fixed as at I II,will serve to translate arm 50, and thereby displaces the ball carriage5| of the variable speed drive 52 in the same manner as in Fig. 3. Therotation of the output cylinder 56 of the variable speed drive 52 isthen led through differential 58 to output shaft 64 controlling a torqueamplifier 66 driving the elevation pinion I6 engaging the elevation rackor ring gear I1 and thereby driving the entire apparatus here shown,together with the guns fixed with respect thereto, in elevation, at arate proportional to the elevation displacement of manual controller I8.This action is exactly similar to that of Fig. 3.

At the same time, this motion of arm 50 moves.

a lever 68 about a pivot 69 and thereby displaces the elevation mirrorIIII, as by means of a suit. able cable H8, or other mechanicalcoupling, to:

displace the line of sight determined by the reticle image III] in thesame direction as the' In addition, the moguns are starting to move.tion of arm 56 moves a lever I6 about a pivot TI and thereby displacesthe ball carriage 86 of vari-; able speed drive 81, whose drive disc 95is driven.

from motor H9 in the manner to be described.

The output cylinder 83 of variable speed drive 3'! drives a gear I2 I-meshing with an elongated pinion I22 which is rotatably mounted on alink I26v coupled to 'lever I6, and which is internally threaded toreceive a threaded shaft I23 movable in translation together with theball carriage 96.

as cylinder 88 turns, pinion I22 is rotated and the screw shaft I23 isthereby screwed in or out. in a sense to restore ball carriage 86 towardits neutral position. In this respect, the device of Fig. 4 is similarto the linkage system 83, 82, I9, 92, 94, 8I of Fig. 3, and serves todelayably rotate I gear I2I by an amount proportional to the dis-.

placement of manual controller I8, and also proportional to the angularvelocity of the guns, and

hence of the target when tracking therewith.

Gear I2I also operates through suitable gearing I24 to rotate a screw 93carrying the nut 95' which supports the pivot 69, andthereby delayablyrotates mirror IOI by the amount necessary to withdraw the line of sightfrom its original advanced position and to displace it from the gunorientation by the proper prediction lead angle: Pivot I1 is madeadjustable under the control of J the range knob 98 and time-of-flightcam 96 in the same manner as in Fig. 3. Gear I2I also adds its motion tothat of cylinder 56 in difierential 58, also as in Fig. 3.

As thus far described, the present system is identical with that of Fig.3, merely replacing the sight I3 by an equivalent sighting device IOI,I03. In order to introduce the super-elevation component of theelevation lead angle, output shaft 59 of differential 58 operatesthrough a worm I26 and a worm wheel I21 to rotate a cam I28, whosefollower I 29 is thereby translated in proportion to the cosine of theangular displacement of shaft 59, and therefore in accordance with thecosine of the angle of elevation of the gun. The displacement offollower I29 correspondingly displaces arm I 3I carrying the rack I32cooperating with a pinion I33, which is thereby rotated through an anglecorresponding to the cosine of the angle of gun elevation. Pinion I33actuates a flexible shaft I34, which in turn rotates a screw shaft I 36rotatably mounted upon arm 50. Screw I36 in this manner translates a nutI3'I mounted thereon, which carries the pivot I38 for lever I6. Thus,the displaces ment of lever I6 produced by manual control I8 is modifiedby an additive component proportional to the cosine of the angle ofelevation. This modification of the displacement of lever I6 produces acorresponding modification of the resultant angular displacement ofoutput cylinder 88 of variable speed drive 31, which thus operatesthrough screw 93 and nut 95 to modify the lead angle of mirror IIII,which is thus controlled both in accordance with the prediction leadangle and the superelevation lead angle to provide the proper resultantlead angle in elevation for effective fire.

Shaft 59 is coupled to torque amplifier 66 driving pinion I 6 withrespect to fixed elevation rack II, similar to the arrangement of Fig.3.

The control of the azimuth mirror I03 is exactly similar to that of theelevation mirror IOI and need not be further described, similar elementsbeing given similar reference characters, but primed. It is to be noted,however, that the angular motion of the line of sight produced byazimuth mirror I03 occurs in the slant plane determined by the gunorientation and the pivot axis I02 of mirror IIlI parallel to the gunelevation trunnions. The azimuth control of the guns, however, isgenerally about a fixed vertical axis, as in Fig. l, or in a horizontalplane. In order to properly control the guns, therefore, it is necessaryto convert angular displacements in azimuth in the slant plane into thecorresponding azimuth angular displacements in the horizontal plane. Asis well known, this conversion may be performed by multiplying the slantplane azimuth values by the secant of the angle of elevation, or bydividing by the cosine of the elevation angle. For this purpose, outputshaft 59 of differential 58', corresponding to output shaft 59 of Figs.2 and 3, which is angularly displaced in accordance with the gun slantplane azimuth, serves to actuate the drum cylinder I4I of a variablespeed drive I42, whose ball carriage I43 is translated in proportion tothe cosine of the angle of gun elevation by means of arm I3I. By sodoing, the disc I44 of variable speed drive I42 is actuated inaccordance with the ratio of the displacement of cylinder I4I to that ofball carriage I43, and will therefore be displaced in proportion to theproduct of the displacement of shaft 59' by the secant of the angle ofelevation.- The output derived from disc I44 is then led to a torqueamplifier 66, similar to that of Figs. 2 and 3, and serves to actuatethe azimuth drive pinion I 3 cooperating with the azimuth ring gear I?to rotate the entire apparatus in azimuth.

As thus far described, the present device of Fig. 4 has added thesuperelevation control and the correction for slant plane data to thedevice of Fig. 3. In order to adjust the settling time in accordancewith the time of flight, range knob 98 and cam 96 actuate a link I46,which in turn is pivoted to a lever I47 having a fixed fulcrum at I43.In this manner, lever I41 adjusts the ball carriage I48 of a furthervariable speed drive I49, whose drive disc I5I is driven at con stantspeed from constant speed motor I I9, in accordance withtiine-of-flight. The output cylinder I52 of variable speed drive I49then drivesv the drive discs 39 and. 96' of variable speed drives; SIand81'. In this manner, the settling time of the variable speed drives 9?and 81 is adjusted 13 in accordance with the time of flight or range ofthe target, so that optimum performance may be obtained both forclose-in targets and for distant targets.

The apparatus of Fig. 2 may be adjusted similarly to allow for close-inor remote targets by adjusting the value of resistor 41 or condenser 46.Preferably, for reasons of simplicity, resistor 41 is made adjustablefor this purpose.

Although the above modifications have been described as using thefriction disc type of variable speed drive, it is to be noted that anyother type of device yielding an output rate of turn corresponding to aninput displacement may be used.

.As many changes could be made in the above construction and manyapparently widely different embodiments of this invention could be madewithout departing from the scope thereof, it is intended that all mattercontained in the above description or shown in the accompanying drawingsshall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A computing gun sight comprising a sighting device mounted on andadapted to be moved with a gun, means for producing a control voltagecorresponding to a desired angular velocity of said gun, meansresponsive to said voltage, and including a speed generator adapted toproduce a speed voltage proportional to the angular velocity of saidgun, for driving said gun and sighting device at said desired angularvelocity, and means for offsetting the orientation of said sightingdevice from that of said gun in a direction opposite to the motion ofsaid gun and in proportion to said angular velocity, comprising meansfor displacing said sighting device displacing said sighting devicerelative to said gun in the same sense as the motion of said gun and inproportion to the rate of chang of said control voltage whereby an aidedtracking control of said sighting device is provided so that 'it may bemore readily tracked with a target.

3. A computing gun sight as in claim 1, further including meansresponsive to a change in said control voltage for initially displacingsaid sighting device relative to said gun in the same sense as themotion of said gun and for delayably removing said initial displacement,whereby said sighting device may be stably and easily tracked with atarget.

RAYMOND C. GOERTZ. HARVARD L. HULL.

References Cited in the file of this patent UNITED STATES PATENTS GreatBritain Mar. 28, 1938

